Transition metal compound

ABSTRACT

a process is provided in which a solid compound of a transition metal of Groups IVA to VIA is ground with at least one polymeric material containing sulphone groups and containing at least two repeat units of the formula: 
     
         --Ar--SO.sub.2 -- 
    
     in which Ar is a bivalent aromatic radical and may vary from unit to unit in the polymer chain. The Ar radical preferably contains two aromatic rings linked together, as in: ##STR1## where X is an O or S atom, a direct link or the residue obtained by removing H from each --OH group present in an aromatic diol. If Ar varies the material is a copolymer. The polymeric material can be a polyethersulphone. 
     The transition metal can be zirconium, vanadium or titanium. Preferably the transition metal compound is a halide such as titanium trichloride.



